This invention relates to snow removel equipment and, more particularly, to motor vehicles which deposit on thoroughfares substances which melt ice and snow or otherwise reduce slipperiness of the thoroughfare.
During the winter in colder climates, fallen snow on streets and thoroughfares often reduces the traction of motor vehicles, and thus presents a safety hazard. One method of alleviating this hazard involves spreading of sand or other coarse, grained material to reduce slipperiness, or alternatively, to spread salt or other material which causes ice to melt, even at temperatures below 0.degree. C. When the temperature of the material to be spread is higher than the snow to be melted, the process is much more efficient. The spreading is performed by placing the salt, sand, or comparable material (known herein throughout as "traction-improving material") into a large bin mounted on the rear end of a motor vehicle, such as a truck. The bin is equipped with an ejection manifold to slowly permit escape of the traction-improving material, draining the bin and releasing the material onto the street surface.
One problem that frequently develops in this method, however, is that in subzero temperatures, moisture in the traction-improving material freezes, causing the particles of traction-improving material to bind together. This, in turn, causes clumping of the traction-improving material which may block the ejection manifold of the bin, preventing the traction-improving material from being released. Further, the traction-improving material may freeze together in a block such that none can be released. Prior methods of solving the clumping problem largely involve physically breaking the clumps or blocks of traction-improving material apart into sizes small enough for release. One such method is to repeatedly strike the exterior side of the bin so that the clumps or blocks break. Another method involves striking the material directly with an instrument--a pick, or a shovel, for example--in order to break the clumps or blocks apart.
These methods are not satisfactory for a number of reasons. First, it is frequently difficult and time consuming to break the clumps or blocks into pieces of small enough size to permit release. Further, the effects of such methods are often deleterious to the bin and may significantly reduce its use life. Repeatedly striking the side of the bin may promote metal fatique and the formation of cracks. Striking the material in the bin directly may have the same effects, or worse, in that such striking presents the possibility of directly punching holes in the side of the bin.
A need has therefore been felt for a method and apparatus for reducing or eliminating clumping of traction-improving materials due to frozen moisture.